add page up/down keys

hn.py

@@ -94,6 +94,18 @@ class Client:
             footer_text = footer_text[:self.cols - 1]
         self.set_footer(footer_text)
 
+    def page_up(self):
+        # scroll up a page (:
+        self.cursor_pos = self.stories_in_a_site-1
+        self.story_pos -= self.stories_in_a_site
+        self.story_pos = 0 if self.story_pos < 0 else self.story_pos
+
+    async def page_down(self):
+        # scroll up down a page :)
+        self.cursor_pos = 0
+        self.story_pos += self.stories_in_a_site
+        await self.load_more_if_needed()
+
     async def handle_input(self):
         c = self.screen.getch()
         story = self.loadedstories[self.topstories[self.story_pos + self.cursor_pos]]
@@ -104,18 +116,18 @@ class Client:
         elif c == curses.KEY_UP or c == ord('k'):
             self.cursor_pos -= 1
             if self.cursor_pos < 0:
-                self.cursor_pos = self.stories_in_a_site-1
+                self.page_up()
-                # scroll up a page (:
-                self.story_pos -= self.stories_in_a_site
-                self.story_pos = 0 if self.story_pos < 0 else self.story_pos
 
         elif c == curses.KEY_DOWN or c == ord('j'):
             self.cursor_pos += 1
             if self.cursor_pos >= self.stories_in_a_site:
-                self.cursor_pos = 0
+                await self.page_down()
-                # scroll up down a page :)
+
-                self.story_pos += self.stories_in_a_site
+        elif c == curses.KEY_NPAGE:
-                await self.load_more_if_needed()
+            await self.page_down()
+
+        elif c == curses.KEY_PPAGE:
+            self.page_up()
 
         elif c == ord('c'):
             # open comments